1. Field of the Invention
The field of this invention relates generally to the repair of gas turbine engine components and more particularly to the repair of turbine components incorporating airfoils with mid-span shrouds therebetween.
2. Description of Related Art
A gas turbine engine includes a compressor that provides pressurized air to a combustor wherein the air is mixed with fuel and ignited for generating hot combustion gases. These gases flow downstream to a turbine section that extracts energy therefrom to power the compressor and provide useful work such as powering an aircraft in flight. Gas turbine engines typically include stationary turbine nozzles that are placed at the entrance of each turbine stage to channel combustion gases into the turbine rotor located downstream of the nozzle. Turbine nozzles are typically segmented around the circumference thereof with each nozzle segment having one or more airfoil vanes disposed between inner and outer bands that define the radial flowpath boundaries for the hot combustion gases flowing through the nozzle. These nozzle segments are mounted to the engine casing to form an annular array.
During operation, nozzle segments are exposed to a high temperature gas stream that can lead to oxidation, corrosion, physical damage, and cracking from thermal cycling. Because nozzle segments are complex in design, are made of relatively expensive materials, and are expensive to manufacture, it is generally desirable to repair them whenever possible.
One known repair process includes brazing cracked turbine components at the crack locations. However, such repair processes are limited by the strength of the brazed joint, which may not be sufficient for further engine operation.